VOC emissions from dry leaf litter and their dependence on temperature

Abstract

Abstract. Emissions of several volatile organic compounds (VOCs) from dry leaf litter at temperatures in the range 20–100 °C are reported for different plant species. The emission rates of ethane, ethene, propane, propene, n-pentane and methyl chloride increase exponentially with temperature and follow the Arrhenius relation. Emission rates up to 650 ng/gdw/h were observed for hydrocarbons at 70 °C, while for methyl chloride emission rates up to 18 μg/gdw/h were observed at this temperature. The emissions are of abiotic origin, which is indicated by activation energies higher than 50 kJ/mol. The emission of VOCs from dry leaf litter decreases in time, due to depletion of the precursor reservoirs. At low temperatures (20–30 °C) the decrease is very slow, but at higher temperatures (80–100 °C) it is noticeable on a timescale of hours. Our results show that hydrocarbons can be produced in the leaf, but the production requires oxygen. Emissions of methyl chloride from dry leaves can be significant for the global budget of methyl chloride.